Proteins when heated with conc. $HNO_3$ give a yellow colour. This is

Which one of the following is an amino acid?

The isoelectric point is a

Glycylalanine is a dipeptide of which amino acids?

The total number of isomeric linear dipeptides which can be synthesised from racemic alanine is

$HC\equiv CH$ $\xrightarrow[HgSO_4]{H_2SO_4} (A)$ $\xrightarrow[(1) NH_3 + HCN]{(2) H_3O^{\oplus}} (B);$ The product $(B)$ of the given reaction is: